smart_auth_plus

A Flutter plugin for Android that wraps Google Play Services' SMS and phone-number authentication APIs with a clean, stream-based Dart API.

Preview

Flutter Phone Field

Features

Feature API used Permission needed?
SMS User Consent SmsRetriever.startSmsUserConsent ❌ None
SMS Retriever SmsRetriever.startSmsRetriever ❌ None
Phone Number Hint Credentials.getHintPickerIntent ❌ None
App Signature Hash Custom SHA-256 helper ❌ None

All results are exposed as sealed classes via Streams – no callbacks, no futures, easy switch pattern matching.

Installation

dependencies:
  smart_auth_plus: ^1.0.1

Quick Start

import 'package:smart_auth_plus/smart_auth_plus.dart';

final auth = SmartAuthPlus();

// Always subscribe BEFORE calling start*
final sub = auth.smsUserConsentStream().listen((result) {
  switch (result) {
    case SmsReceived(:final message):
      print('Got SMS: $message');
      // Extract OTP from message here
    case SmsCanceled(:final reason):
      print('Canceled: $reason');
    case SmsError(:final code, :final message):
      print('Error $code: $message');
  }
});

await auth.startSmsUserConsent();

// When done:
sub.cancel();
auth.dispose();

API Reference

SmartAuthPlus

// 1. Subscribe
Stream<SmsResult> smsUserConsentStream()

// 2. Start
Future<void> startSmsUserConsent({
  String? senderPhoneNumber,   // optional filter
  Duration timeout = const Duration(minutes: 5),
})

SMS Retriever (automatic, no dialog)

Your SMS must end with the 11-character hash from getAppSignature().

// SMS format: "Your OTP is 123456\n\nFA+9qCX9VSu"

Stream<SmsResult> smsRetrieverStream()
Future<void> startSmsRetriever()

Cancel

Future<void> cancelSmsListener()

Phone Number Hint

Stream<PhoneHintResult> phoneHintStream()

Future<void> requestPhoneNumberHint({
  String title = 'Select phone number',
  String subtitle = 'Choose a number for verification',
})

App Signature Hash

// Call once during development; never in production
Future<String?> getAppSignature()

Dispose

void dispose()  // Call in widget dispose()

Result Types

SmsResult (sealed)

switch (result) {
  case SmsReceived(:final message):  // Full SMS body
  case SmsCanceled(:final reason):   // User dismissed or timeout
  case SmsError(:final code, :final message): // Platform error
}

PhoneHintResult (sealed)

switch (result) {
  case PhoneHintSelected(:final phoneNumber): // E.164 number
  case PhoneHintCanceled(:final reason):
  case PhoneHintError(:final code, :final message):
}

SMS Retriever – App Signature

  1. Run your app in debug, tap Get Hash (or call getAppSignature()).
  2. Note the 11-character result, e.g. FA+9qCX9VSu.
  3. Append it to every OTP SMS your server sends:
Your OTP code is 123456

FA+9qCX9VSu

⚠️ The hash differs between debug and release builds. Generate one for each keystore.

Requirements

  • Flutter ≥ 3.10
  • Dart ≥ 3.0
  • Android minSdk 21
  • Google Play Services on device

License

BSD-3-Clause

Libraries

smart_auth_plus
SmartAuthPlus - Flutter plugin for Android SMS/Phone authentication APIs.
smart_auth_plus_method_channel
smart_auth_plus_platform_interface